Riboflavin

Question 1

What are the structural differences between riboflavin, FMN, and FAD?

Answer 1

Riboflavin - ribitol group, and flavin group.
the differences between riboflavin and FMN is that FMN has an additional phosphate group added

FMN - flavin mononucleotide
(nucleotide group = phosphate group + sugar + nitrogenous base)

FAD - flavin adenine dinucleotide
(dinucleotide = 2 phospahte groups + nitrogenous base + sugar)

Question 2

From the 4 functional categories of vitamins, what category (categories) does riboflavin belong to?

Answer 2

• coenzyme

- electron acceptor

Question 3

How does the structure of riboflavin help it to function in redox reactions?

Answer 3

double bonds allow for resonance stabilization for the acceptance of electrons without turning into a highly reactive radical

Question 4

In which enzyme of the TCA cycle does riboflavin serve as a coenzyme?

Answer 4

succinate dehydrogenase - the bridge between the TCA cycle and ETC (Complex II)

• uses coenzyme FAD in the TCA cycle
• part of complex II of the ETC

Question 5

How was riboflavin discovered?

Answer 5

heat-stable, water-soluble rat growth factor

yellow-green fluorescence found in thiamine-free extracts of yeast, liver, and rice bran
the color intensity (fluorescence) was proportional to the effect of growth
Some of the extracts that were found were ovoflavin- in egg whites
lactoflavin extracted from whey protein